Frame grid



y 1960 F. H. GRIMONE ET AL 2,936,392

FRAME GRID 5 Sheets-Sheet 1 Filed March 26, 1958 Fig.2

47 INVENTORS JAMES M. CALEHUFF TTORNEY y 1960 F. H. GRIMONE ET AL2,936,392

FRAME GRID Filed March 26, 1958 5 Sheets-Sheet 2 Fig.5

A RNEY y 1960 F. H. GRIMONE ET AL 2,936,392

FRAME GRID Filed March 26, 1958 5 Sheets-Sheet 5 I INVENTORS 1mg. 10JAMES M cm EHq F FRANK H- GR/ 5 BY WWM a ATTORNEY y 1960 F. H. GRIMONEET AL 2,936,392

FRAME GRID 5 Sheets-Sheet 4 Filed March 26, 1958 mus??? TTORN EY y 10,1960 F. H. GRIMONE ET AL 2,936,392

FRAME GRID Filed March 26, 1958 5 Sheets-Sheet 5 0 JAMES fi aL /UFFFRANK H. GR/MONE United States Patent FRAME GRID Frank H. Grimone,Emporium, and James M. Calehulf, Montoursville, Pa., assignors, by mesneassignments, to Sylvania Electric Products Inc., Wilmington, Del., acorporation of Delaware Application March 26, 1958, Serial No. 724,184

3 Claims. (Cl. 313-348) This invention relates generally to electrondischarge 'devices and more specifically to the internal arrangement orelectrodes in an electron discharge device and the electrode structures.The vast majority of machine fabricated electron tubes use gridelectrodes of the side rod supported type, whereinlateral grid wires arehelically wound around two or more copper side rods and attached theretoin peened over notches. The side rod supported type electrode has metwith exceptional success in helping to meet demands placed on tubes incircuit use; however, many tube types have been pushed to what appearsto be a maximum due to heat dissipation limitations in the gridstructures.

'A few tube types have been fabricated using a planar type gridelectrode having a lateral grid wire supporting frame with potentiallygreater heat dissipation characteristics than the majority of side rodsupported electrode types. The cost of most prior art frame grids,however, has been either excessive or made competitive by sacrifice ofcertain desirable characteristics. Also most prior art planar type gridelectrode forms require a radical departure from known assemblytechniques. For example, several prior art concepts teach the use of acurved and rather flexible frame wherein lateral grid wires may beattached under relatively low tension and brought up to usable tensionby flattening the frame in final assembly. Use of such a structureaggravates assembly problems. The prior art also suggests the use of acompletely flat frame which might be readily assembled in a completetube; however, there is no suggested provision for avoiding distortionin either relatively high temperature assembly processing steps or insubsequent high temperahire use. A grid structure which alleviates manyof the problems of the prior art is shown in co-pending patentapplication, Curry et al., Serial Number 674,659, filed July 29, 1957,and assigned to the same assignee as the present application. 1

Thus it is an object of this invention to improve usable heatdissipationcharacteristics of frame type grid electrodes.

It is a further object of this invention to maintain tension andparallel configuration of lateral grid wires under various operatingtemperatures and conditions in a frame type grid electrode.

It is a still further object of this invention to shape a frame typelateral grid wire supporting structure so as to obtain exceptionallystable characteristics in an electron discharge device having an anodeand cathode along with one or more grid electrodes.

Briefly, the invention in one aspect comprises a grid electrode having aframe formed to provide a central aperture having two side legs and twoend legs wherein the side legs include a raised bead for holding theterminal ends of the lateral grid wires above the side leg portionadjacent the bead and wherein the side legs also include externalstrengthening channels drawn in part from the portion of the frameinternal the beads. The end legs are weakened or stretched and the sidelegs bent or roice tated to increase lateral grid wire tension and bringthe side leg aperture edges into contact with the lateral grid wires.

For a better understanding of the present invention, together with otherand further objects, advantages and capabilities thereof, reference ismade to the following disclosure and appended claims in connection withthe accompanying drawings in which:

Fig. 1 shows a frame blank with attached lateral grid wires; and

Fig. 2 shows an enlarged side view of the notched and peenecl grid wiresupporting bead; and

Fig. 3 shows a number two grid after forming; and

Fig. 4 shows a cross section of the grid of Fig. 3; and

Fig. 5 shows a punch and die for forming grids; and

Fig. 6 shows the face of a punch insert; and

Fig. 7 shows the punch and die set of Fig. 5 in closed position; and

Fig. 8 shows a number one grid electrode; and

Fig. 9 shows a cross section of the grid before forming; and

Fig. 10 shows a cross section of the number one grid of Fig. 8; and

Fig. 11 shows one view of an assembled tube mount using the grids ofFig. 3 and Fig. 8; and

Fig. 12 shows a blow-up of the tube mount of Fig. 11; and

Fig. 13 shows a cut away view of the tube mount of Fig. 11.

Referring to Fig. 1, there is shown a grid frame blank 21 havingmounting tabs 23 and coined ridges or beads 25. Lateral grid wires 27may be attached at their terminal ends to raised head 25 in any mannersuch as welding or brazing; however, in the preferred embodimentdisclosed, lateral grid wires 27 are attached to beads 25 by a notchingand peening process, the result of which is best seen in Fig. 2.

Fig. 2 shows an enlarged sectional side view of frame blank 21 andraised bead 25. A notch somewhat similar to the notches 29 is formed inthe head 25 for supporting the terminal end of a given lateral grid wire27. Then, after the lateral grid wire has been inserted, the notch ispeened or closed by a peening tool which deforms the bead somewhat asshown at 31. If desired the lateral grid wires may be attached to theupper surface of the beads by welding, brazing or any other means formaking a relatively integral connection between the grid wires and thebead material. Also it may prove desirable in some grid structures toform notches 29 and attach the lateral grid wires by brazing, welding,or by means other than peemng.

Referring again to the frame blank of Fig. 1, the grid blank 21 may beformed from any type of sheet metal material selected from a range ofmaterials having suitable strength, thermal and electricalcharacteristics. To arrive at a frame blank 21 such as shown in Fig. lthe selected sheet metal material which for example only may comprisenickel clad steel, is preferably first fed through a coining or formingprocess to provide ridges or beads 25 and then stamped or cut to providea central aperture 33 along with mounting tabs 23. The resultingstructure can be considered as having two side leg portions 35 and twoend leg portions 37. After the blanks have been coined and then stampedor cut it may be desirable to soften or heat treat the material beforeinsertion of the grid wires and final forming.

Fig. 3 shows a completed grid formed from a grid blank of Fig. 1 by aprocess to be hereinafter described in detail. As can be seen, thestructure of Fig. 3 differs from the structure of Fig. 1 in that the endlegs 37 include end indentations or dimples 41 and the side legs includea channel 43 and side wings 45. As best seen in the cross section Fig.4, the forming process tends to rotate the side legs so as to bring theinternal or side aperture edges 47 into contact with the lateral gridwires Before considering the important advantages which arise out of thegeneral frame shape ultilized, reference is made to Figs. through 7which show the punch and 'die unit used to form a grid blank intothefinal shape desired. Referring to the particular structure shown inFig. 5 it will be seen that the topdie 48 set includes a cylindricalshaft 49 which is integrally attached to the punch insert and stripperportion 51. Top punch 53 acts as a spring loaded device by virtue of theforce applied by upper spring 54 between the shoulder 55, which isattached to shaft 49, and the upper surface of top punch 53. The bottomdie set, generally shown at 57, comprises a die body 59 and a bottompressure pad 61 which is spring loadedrelative to the die body 59 by aspring 62 surroundinglower shaft 63. The'lower shaft 63 may beconsidered to be integrally attached to the bottom pressure pad 61 so asto extendthrough an aperture, not shown, in the lower die body. Ifdesired shaft 63 could be integrally attached to the lower die body andmounted for sliding movement in an aperture, not shown, in pressure pad61 so as to allow sliding movement of pressure pad 61 relative to shaft63, against the forceof lower spring 62. Of course the end of shaft 63cannot be allowed to penetrate through the upper surface of pressure pad61.

The bottom surface or the face of punch insert 51 can best be seen inFig.6. The larger portion of the face comprises a substantially flatland 65 provided with two parallel integral elongated embossments 67 ofrelatively convex contour positioned to strike the side legs of theframe blank. There are also two spaced dimpling embossments 69, also ofconvex contour, positioned between the side embossments 67 to strike theend legs of the frame blank.

Bottom pressure pad 61 comprises a flat land portion 71 and twoelongated grooves 73 which are intended to receive the frame materialpunched by punch insert embossments 67.

To start the forming process, a grid blank, as shown in Fig. 1,including attached lateral grid wires, is placed on bottom pressure pad61 with the lateral grid wire side of the blank in the upward position.The top die set 48 is moved toward the bottom die set 57 by applying aforce through shaft 49 from either conventional hydraulic or mechanicalmeans or, if desired, through the use of a conventional air cylinderdrive, not shown. The top die set 43 descends until edges 75 of the toppunch 53 contact the frame blank and press it firmly against thepressure pad or lower die insert 61. Since the edges 75 of the top punch53 are slightly angled the lower sharp portions tend to hold the frameblank firmly and limit or block flow of material from externalthe edges75 during subsequent portions of the forming process. The internal wingforming indentations .77 .in the lower die body 59 form the wings 45, asshown in Figs. 3 and 4, as the bottom pressure pad or lower die set 61is moved downwardly by the force applied by top die set 48 against thecompressive force of lower spring 62. When the bottom pressure pad 61bottoms, i.e., is stopped in the position shown in Fig. 7, by either astop attached to lower shaft 63, not shown, or any other type ofstopping means, top punch 53 also stops; howeventhe upper punch insert51continues to travel downwardly compressing upper spring 54. As theelongated embossments 67 on the face of punch insert 51 strike the framegrid blank 21, channels start to form in the side legs of the frameblank and internal portions of the side legs are drawn into grooves 73in pressure pad 61.. Since a large portion of the material taken to formthe channels is taken from the side leg portions internalthechannelsythe spacing between the parallel, beads 25 on the frame blank'4 tends to increase and stretch the lateral grid wires 27 attachedthereto. Before the upper punch insert 51 completes its downwardstrokethe upper surfaces of both end legs 37 of the blank 21 are struckby the punch insert dimpling embossment 69. Since the bottom pressurepad 61 is generally .flat beneath the area to be struck by dimplingembossment 69, the resulting dimple'tends to reduce the thickness of theend legs 37 or weaken them so that the final formation of the frame gridsidechannels 43 tends to stretch all of the lateral grid wires in arelatively uniform manner. Punch insert 51 then is retracted relative totop punch 53 which is held in position by action of spring 54. As shaft49 is further retracted the punch insert 51 picks up the top punch 53and the complete top die set 48 is retracted back to its startingposition in the forming cycle. Any formed frame which tends to stick tothe punch insert 51 is automatically stripped therefrom through relativemovementbetween punch insert 51 and top punch 53 while shaft 49 is beingretracted. .After the forming step it has been found desirable, in someembodiments, to fire the complete grid primarily for cleaning purposes.

Before considering various spacings between grid struce tures which maybe fabricated using the inventive. concepts disclosed and claimedherein, particular note is made to the final clearance between punchinsert 51 and the bottom pressure pad 61 with regard to land surfaces 65and 71. By allowing suflicient clearance between lands 65 and 71, thefinal forming pressure of the punch and die set as shown in Figs. 5through 7 tends to rotate theside legs 35 of the frame grid electrodeblankso as to bring the internal aperture edges .47 into contact withlateral grid wires 27. This final forming action tends to establish aplanar relatively flat grid aperture area by stretching lateral gridwires 27 across the raised plane established by the internal apertureedges 47. It is to be particularly noted that the lateral grid wires aresup ported by the beads 25 above the upper surface of the side legsadjacent the side legs and due to the final rota.- tion or bending ofthe side legs contact is made between the lateral grid wires 27 andinternal aperture edges 47. As will hereinafter be brought out, not onlydoes this contact between the lateral grid wires 27 and the apertureedges 47 establish a planar grid aperture but it also provides contactwith the frame portion through which heat may be dissipated from lateralgrid wires 27 directly to the frame as well as through beads 25. Othermeans of rotating or bending theside legs 35 .of the frame blank willoccur to those skilled in the art. For example, additional embossmentscould beincluded on theland 71 of bottom pressure pad 61. i

It is to be understood that the drive mechanism for the punch and dieset shown in Figs. 5 through 7 may be any conventional structure wellknown to thoseskilled in the art and thus need not be shown or describedin detail herein. It should be further, understood that the relativespacings between the various embossments and grooves in the completepunch and die set are merely representative, and the location ,of the.grid electrode in the final mount assembly may dictate spacings otherthan shown. For example, in Figs. 8 and 10 there is shown atypicalnumber one grid which, is positioned in a final tube'ass'embly adjacentthe cathode. The gridshown in Fig. 3 may be considered to be the numbertwo grid which is finally spaced adjacent the anode in agiven tubemount. By comparing the shapes of these two grids it canbe seen thattabs 23 in the grid of Fig. 3 are spaceddiiferently than the tabs 23 ofthe grid shown in Fig. 8,"though the general configuration remainssimilar. Referring to Fig. 8 it may also be seen that the channels 43are substantially in line with the tabs "23 while in thegrid structureof Fig. 3 the channels 43 are completely'external tabs 23. a e I i IClearance problems inthe final assembly'may dictate, the shape ofvarious cut-out portions'ineither the end legs or side legs of any givengrid. Thus in the grid shown in Fig. 8 a cathode clearance cut-out 83has been provided in end legs 37.

In Fig. 9 there is shown a cross section of a typical number one gridblank before forming which can be compared with the cross sectional viewof Fig. 10 after forming. As can be seen, not only does the formingprocess provide strengthening side channels 43 by flowing metal from theside leg portions internal channels 43, but also the final formingprocess tends to rotate the side legs so as to bring internal apertureedges 47 into contact with the lateral grid wires 27 to form somewhat ofa bridging structure. Thus in the number one grid as well as the numbertwo grid the lateral grid wires are attached between raised beads abovethe upper surface of the frame side legs adjacent the beads 25 and yetin contact with the side legs at internal aperture edges 47.

Referring to Figs. 11 through 13 there is shown a typical stem andelectrode mount using the number two grid of Fig. 3 and the number onegrid of Fig. 8. The completed mount may comprise an exhaust stem 91 withintegrally related terminal pins SE3 attached to the various heater andelectrode portions of the electrode mount shown generally at 95.

Referring specifically to the electrode mount shown in Figs. 12 and 13it can be seen that the anode 101 is in two substantially similar partsand formed to enclose the remainder of the electrodes on all sides otherthan the top and bottom. Lead 103 which is connected to a tab on anode101 acts as the anode lead extending outside of the tube envelopethrough the top portion. Frame grid 105 acts as a number two grid beingpositioned adjacent anode 101. Grid 167 acts as the number one gridbeing spaced between grids 105 and cathode 10s. Heater Wires 111 areprovided internal the cathode sleeve. Apertured shield element 113surrounds the grid and cathode portions acting as a beam formingelectrode. As can be clearly seen in Fig. 12 upper and lower micaelements 115 are perforated to receive the supporting tabs of thevarious electrodes.

As can be seen in Fig. 11 and Fig. 13 the grid wires of the number twogrid are accurately spaced in the electron stream flow from cathode toanode so as to be immediately behind corresponding lateral grid wires inthe number one grid. Due to the original strength of the supportingframe 21 and its excellent heat dissipation characteristics, it is notonly possible to make certain that the grid wires of one grid areoriginally positioned immediately behind the associated grid wires ofthe next grid but also, due to the improvements in grid structurestaught herein, this relationship remains substantially true duringsubsequent processing and use. With regard to grids of the side rodsupported type it has been found that grids made according to theteaching set forth herein are far more stable both mechanically andelectrically. There is less variation of electrical characteristics fromtube to tube on the production line. There is less change in theelectrical characteristics during the useful life of the tube. In part,because of the accurate spacing of the lateral grid wires there isbetter control of cut-oflf. Further the plate to screen grid currentratio is generally improved.

It is believed that these improvements stem in part from the fact thatheat is more rapidly dissipated in the relatively larger frame than ispossible in conventional side rods. With regard to frame grids of theprior art it is believed that the improvements noted herein stem in alarge part from the fact that formation of the grid so as to bring theframe aperture edge into contact with the lateral grid wires not onlyallows control over the original grid tension but also allows directcontact for heat fiow between lateral grid wires and the side frame legsso as to maintain desired tension. In addition, by controlling theamount of rotation of the frame side legs in the forming processaccurate control is maintained over the grid minor axis measurement,i.e., the distance between similarly positioned lateral grid wires inthe two halves of either the number one grid or the number two grid.

Grid structures of the type disclosed herein and made in accordance tothe process taught herein have been made from nickel clad sheet metal,and nickel wire has been used for the lateral grid wires. If desired theunits may be gold plated or blackened in part where desirable to improveelectrical characteristics. Other material may be used, and the choicewill depend upon ease of forming and the electrical characteristicsdesired.

While there has been shown and described what is at present consideredthe preferred embodiment of the present invention, in view of thisdisclosure it will become obvious to those skilled in the art thatvarious changes and modifications may be made without departing from theinvention as defined in the appended claims.

Having thus described our invention, we claim:

1. In a frame grid structure the combination comprising a sheet metalframe formed to provide a central substantially rectangular aperturedefined by the internal edges of a pair of spaced end legs and theraised internal edges of a pair of spaced side legs, a longitudinallyextending raised head on the upper surface of each side leg in spacedrelationship with the internal aperture edge, and a plurality ofsubstantially parallel lateral grid wires mounted to extend between andsecured within lateral bead grooves above the upper surface of said sidelegs adjacent said beads and in contact with said side legs adjacent theaperture edge.

2. In a frame grid structure the combination comprising a sheet metalframe formed to provide a central substantially rectangular aperturedefined by the internal edges of a pair of spaced end legs and theraised internal edges of a pair of spaced side legs, a longitudinallyextending raised bead on the upper surface of each side leg in spacedrelationship with the internal aperture edge and a longitudinallyextending channel spaced external the bead, and a plurality ofsubstantially parallel lateral grid wires mounted to extend between andsecured within substantially closed lateral bead grooves above the uppersurface of said side legs adjacent said beads and in contact with saidside legs adjacent the aperture edge.

3. In a frame grid structure the combination comprising a sheet metalframe formed to provide a central aperture defined by the internal edgesof a pair of spaced end legs and the raised internal edges of a pair ofsubstantially parallel spaced side legs, a longitudinally extendingraised head on the upper surface of each side leg in spaced relationshipwith the internal aperture edge, and a plurality of lateral grid wiresmounted to extend between and secured within substantially lateral beadgrooves above the upper surface of said side legs adjacent said beadsand in contact with said side legs adjacent the aperture edge.

References Cited in the file of this patent UNITED STATES PATENTS2,624,100 Foulkes Jan. 6, 1953 2,829,298 Gude Apr. 1, 1958

